Green Sahara seawater greenhouses

and cardboard evaporative coolers outdoors...

http://nextbigfuture.com/2013/05/green-deserts-by-using-seawater-to-cool.html#more

http://saharaforestproject.com/projects/qatar.html

www.newscientist.com/article/mg21829182.100-to-green-the-deserts-just-add-seawater.html?full=true

It's a really interesting concept: a greenhouse that cools rather than warms. A "coolhouse" perhaps? I like the careful use of salt water, and the idea that, overall, it intends to try to re-vegetate this part of the desert in Qatar.

But is it economically feasible? $6,000,000.00 USD for a cucumber garden? I realize Qatar has some money to burn, but I still have to think there's got to be a better way.

I'm curious if this can become a sort of "breeder" program that can be picked up and moved down the coast once the soil has been improved and there are trees for shade. That might help make it better.

It looks really good from an engineering perspective. I think it relies very heavily on external technologies, resources, financing, and ideal conditions to be feasible.

I was looking into greenhouses and concentrated solar power for a different project. My concern was the desert wind storms (or stronger Haboobs) would scratch all the glass, reflective CSP panels, and solar panels decreasing their usefulness in a couple years.

I am going to guess/hope that a lot of the $6 million was initial R&D. They may have also not had much incentive to optimize the design for cost savings.

I don't think the need for desalinated water will change significantly anytime soon.

There is a lot that can be done with seawater and brackish water. I did some research on it a few years ago for a development project.

You can find some good information in "Saline Agriculture: Salt-Tolerant Plants for Developing Countries ( 1990 )" and at the US Salinity Laboratory website.

I also received a note from a gentleman in India that explained how to grow crops with seawater in the Sunderbans. He wrote, "There are two tricks in using saline water for irrigation of plants. One is to use salt tolerant plants and the second is not to allow the salinity in the root zone to rise beyond the tolerance limit of the plants. Therefore dig a trench on the ground next to the sea shore. The trench should start at a high level and run downhill till it reaches the sea. Fill the trench with sand and plant salt tolerant plants in the trench. Coconut, Casuarina, spinach, and Salvadora oleoides are some of them. You may test some other species found growing near the coast in your own country. All mangrove plants can tolerate salinity. When irrigating these plants, water is introduced at the highest level of the trench and continue to irrigate till the water starts flowing out of the trench. This procedure may be repeated every second day. The excess water, coming out of the lower end of the trench, would flow back into the sea. Sea water contains all the mineral elements that a plant needs, except for phosphate. Therefore apply super phosphate to the plants. If the salinity of the water is moderate, with about 2% salt in it, one can even grow wheat, cotton or sugarbeet by this method. One can also make use of raised beds, made of sand for this type of cultivation, but trenches are easier to make and to maintain."

I received an update from the gentleman in India. He wrote: "you need not apply phosphate or any other fertilizer. Just apply once a month any non-composted, high calorie organic substance (e.g. green leaves, prawn shells, fish waste) at the rate of about 2.5 g (dry weight) per sq.m., once a month to the beds. This serves as food for the soil bacteria and they proliferate, taking up the necessary minerals from the substrate. Bacteria have almost 15% minerals on dry weight basis as against only 5% in plants. When the bacteria die, they make the minerals available to the plants."

I am waiting for a report from one of his associates on a raised-bed gardening project in the Sundarbans. I will start a new thread when I receive it.